Parts for your 2016 Subaru Legacy-Throttle position sensors

2016 Subaru Legacy throttle position sensor (TPS): what it does and how to look after it

Based on the Subaru factory service manual for the 2015–2017 Legacy/Outback (FB25 2.5L and EZ36 3.6L), Subaru Global Service Information, and OEM parts catalogues, the 2016 Subaru Legacy absolutely uses a throttle position sensor. It’s part of the electronic throttle control (drive‑by‑wire) throttle body assembly and is configured as dual, redundant sensors (TPS 1 and TPS 2). The engine control module monitors these against the accelerator pedal position sensor, with relevant OBD‑II fault codes including P0121, P0122, P0123, and P2135 documented in Subaru diagnostic literature and standard SAE references.

The TPS tells the ECM exactly how far the throttle plate is open, letting it manage fuel, spark, idle speed, cruise control and transmission shift timing smoothly. Because it’s a drive‑by‑wire setup, the TPS signal works alongside the pedal sensor to confirm intent and actual throttle angle. Two independent TPS tracks inside the throttle body provide safety redundancy, if their signals don’t agree, the ECM can drop into a limp‑home mode to protect the engine and drivetrain.

• Common signs of trouble: hesitant take‑off, surging, rough or high idle, sudden loss of power, cruise control dropping out, and the MIL illuminating.
• Scan data typically shows erratic or mismatched TPS percentages, often with correlation codes.

The TPS on this model isn’t a routine service item and generally lasts a long time. Sensible upkeep includes keeping the throttle body and intake tract clean (without dousing the sensor area), ensuring the battery and grounds are healthy, and inspecting the throttle body connector for moisture, corrosion or pin tension issues. When cleaning, use sensor‑safe intake cleaner sparingly and avoid forcing the throttle plate by hand.

On the 2016 Legacy the TPS is integrated into the throttle body and is not usually serviceable on its own. Replacement typically means fitting a complete throttle body assembly with a new gasket. Best practice is to depower the vehicle, remove the intake duct, unplug the connector, swap the unit, torque the fasteners evenly, and perform the electronic throttle/idle relearn with a capable scan tool (or follow Subaru’s prescribed learn procedure). After replacement, clear codes, verify APP/TPS correlation in live data, check for vacuum leaks, and confirm stable idle. Quality OEM or reputable reman parts are the smart choice, and owners can expect these units to go well past 150,000 km unless a fault or contamination brings them undone.

Popular questions

Does a 2016 Subaru Legacy have a separate throttle position sensor?
The 2016 Legacy has the TPS built into the electronic throttle body as a dual‑sensor package. There’s also a separate accelerator pedal position sensor on the pedal. The TPS isn’t typically available as a standalone part.

What are the signs the TPS on a 2016 Legacy is failing?
Owners often notice hesitation, surging, a stuck‑high idle, cruise control switching off, or the car going into limp mode. Fault codes like P0121 or P2135 and odd TPS percentage readings in scan data are strong clues.

Does the throttle need a relearn after replacing the TPS/throttle body?
Yes. After fitting a new throttle body, the ECM needs an electronic throttle/idle relearn. Using a scan tool is best, procedures generally involve a key‑on cycle and an idle stabilisation period without touching the pedal, followed by a short drive to finalise learning.